When a driver drives his motor vehicle at a high speed, he may be affected by severe glare, flare, and etc., e.g., strong sunlight, high beams at night from the vehicle in the opposite direction, reflected light of snow in winter, sudden change of light in tunnels, and eyestrain and instantaneous blindness caused thereby are important reasons for traffic accidents. Protecting the driver's eyes from not being stimulated by the glare outside is very important for improving driving safety.
At present, in order to prevent eyestrain of the driver caused by glare stimulation, a sun visor is often provided on the front window of the vehicle. For the traditional sun visor, when in use, the visor body is rotated down to block upper portion of the light rays to the driver's eyes, which makes sure that the driver can clearly see the outside of the vehicle. When light shading is not needed, the sun visor is turn down.